1. Field of Invention
The present invention relates to an instrument for endoscopic surgery with principal applications to laparoscopy (abdominal endoscopic surgery) and thoracoscopy (endoscopic surgery of the thorax).
2. Description of Related Art
This endoscopic surgical instrument belongs to the species of those having a handle extended by an elongated tubular part, itself connected by a multidirectional joint to a terminal or distal part able to carry a tool, control means being provided in the handle area to control the angle of the terminal part by means of a mechanical wire or cable transmission passing inside the tubular part, also traversed by a central tool control cable.
An endoscopic surgical instrument of this type is known from European Patent Application EP 0 646 356 A2. Because of its articulated distal end, such an instrument offers the surgeon access to a larger part of the surgical field, enabling him to choose the direction of approach and making the procedure more effective. This, the surgeon is freed of the constraints linked to endoscopic surgery, particularly passage through a fixed point (such as the point of entry into the abdomen).
However, the embodiment described and illustrated in the European patent application referred to above remains imperfect, and has in particular the following drawbacks:
In the embodiment subject of European Patent Application EP 0 646 356 A2, it is not possible to rotate the distal part of the instrument about its own lengthwise axis from the control element located on the handle. Moreover, this control element is located in the back part of the handle, which is a non-ergonomic position that could lead to inaccurate control.
When the above document is reduced to practice, at least in certain embodiments, the transmission wires have to be crossed, reversing the direction of movement of the distal end of the instrument relative to the control. Moreover, the crossing of the wires complicates their path and brings about friction. This crossing also reduces the free space available for controlling the tool on the instrument, for example the forceps opening and closure control.
Since the transmission wires of the instrument according to document EP 0 646 356 A2 are anchored to the ball joint of the distal part, the maximum authorized displacement remains relatively limited.
Moreover, in the instrument according to the aforesaid document, there is no provision for locking the orientation mechanism in any position that is to be temporarily maintained; thus, as soon as the control is released, the mechanism returns to the starting position (central position), urged by springs.
Finally, the instrument described in document EP 0 646 356 A2 is not impermeable, except for an O-ring located on the ball joint, and is difficult to clean.
The goal of the present invention is to eliminate all these drawbacks by providing an endoscopic surgical instrument that is improved both in its control, rendered particularly ergonomic, and in its utilization options, while ensuring impermeability.
For this purpose, the invention relates essentially to an endoscopic surgical instrument of the type referred to at the outset wherein:
the control means, located in the front part of the handle, comprise a spherical crown having a center and an axis, the crown being orientable in all directions inside a cone relative to its center and being rotatable about its axis,
the spherical crown is linked at an angle to a part controlling wires or cables, the proximal ends of the transmission wires or cables being attached to said control part,
means, are provided to transmit the rotation of the spherical crown about its axis to an internal element mounted to rotate about the axis of the elongated tubular part, rotation of this element being transmitted, through the aforesaid joint, to the terminal part in order to orient this terminal part around its own lengthwise axis, and
means, are provided for non-permanent locking of the aforesaid joint at anyangle.
Preferably, the spherical crown is connected to the internal element mounted to rotate about the axis of the elongated tubular part by means of a gimbal mechanism.
Thus, the invention provides an endoscopic surgical instrument, characterized mainly by a single control element whose orientation enables the distal part of the instrument to be articulated at any angle, and whose rotation (about its own axis) enables the orientation of this distal part about its lengthwise axis to be controlled. The position of this single control element, in front of the handle, is ergonomic and reflects the simple rotation controls existing in the rigid, straight-line instruments available on the market and habitually used by surgeons.
In one embodiment of the invention, the output element of the gimbal mechanism is coupled to the central tool-controlling cable by means of a gear train able to transmit the rotary movement from the outside of the elongated tubular part to the inside thereof, the gear train comprising a gear linked rotationally to the output element of the gimbal mechanism, another gear rotationally linked to a central rod linked to the tool-controlling cable, and intermediate pinions, engaging the aforesaid two gears.
According to another embodiment of the invention, the output element of the gimbal mechanism is coupled to the central tool-controlling cable by magnetic means, in particular permanent magnets, with interposition of a fixed nonmagnetic impermeable wall.
According to another embodiment of the invention, the output element of the gimbal mechanism is coupled directly to an internal rotating tubular element surrounding the tool-controlling cable and forming a rotating assembly with the latter.
According to a simple arrangement, the control spherical crown is itself the operating element activatable by the user.
However, in a preferred embodiment the spherical crown is surrounded concentrically with an external operating ring to which it is coupled angle- and rotation-wise by magnetic means, in particular permanent magnets, with interposition of a fixed nonmagnetic impermeable wall. This design of the control, with an external element manipulated by the surgeon, coupled to an internal control crown, provides a sealed design, as the magnetic coupling produced through the fixed impermeable wall allows identical positioning and movement of the spherical control crown and the operating ring without mechanical complications.
Since such an endoscopic surgical instrument is normally provided with a separate control to activate the tool carried by the instrument, particularly a control for opening and closing a forceps by a small-amplitude translational movement, additional sealing means are also provided in the form of flexible sleeves located in the proximal and distal parts. Since an internal sealing sleeve located at the distal part is subject to torsion when this distal part rotates about its lengthwise axis, this torsion has to be limited in order not to tear the sleeve. For this purpose, the instrument also advantageously has mechanical means for limiting the rotation of the distal part. In one particular embodiment, these means comprise a part mounted to rotate freely in the handle, said part being entrained rotationally by a first finger linked rotationally with the internal element receiving the rotational movement of the spherical crown, the aforesaid part itself having a second finger that abuts a fixed part. Such a mechanism allows rotation around slightly less than two complete turns.
According to another aspect of the invention, the multidirectional joint between the elongated tubular part and the terminal or distal part of this instrument comprises a free intermediate ball joint able to describe an orientation movement with respect to a female ball joint integral with the front end of the elongated tubular part and also with respect to another female ball joint integral with the back end of the terminal part of the instrument, all these ball joints being concentric, and the transmission wires or cables passing by the periphery of the intermediate ball joint, their front ends being connected to the terminal part of the instrument.
Thus, the instrument has a double intermediate ball joint, for example with a displacement of approximately xc2x130xc2x0 for each of the two female ball joints relative to the intermediate ball joint so that the distal part can be oriented over approximately xc2x160xc2x0 in all directions of space.
The intermediate ball joint preferably has a shaped diametral passage traversed by the central flexible tool-controlling cable carried by the instrument in order to guide this flexible cable which, itself, positions the intermediate ball joint at the ideal orientation corresponding to an angle equal to half the total angle between the elongated tubular part and the distal part. The appropriate guidance of the central flexible cable also ensures firm application of the two female ball joints against the intermediate ball joint, while avoiding a change in length of this cable during the angling to prevent any undesired opening or closure of the tool, particularly a forceps.
Advantageously, the back ends of the transmission wires or cables are anchored to an internal spherical control element whose diameter is greater than that of the intermediate ball joint, preferably a diameter equal to or double that of the intermediate ball joint; thus, the angular displacement of the control element is doubled at the distal part: a xc2x130xc2x0 movement of the control element, compatible with the mechanical structure and with ergonomic requirements, allows the distal part to be oriented by xc2x160xc2x0.
According to another aspect of the invention, the instrument has means for locking the aforesaid joint, which is in particular a ball joint as defined above, hence means for immobilizing the terminal or distal part of the instrument at the angle given by the control means. Advantageously, the nonpermanent locking means of the joint between the elongated tubular part and the distal part of the instrument comprise elements that act by gripping the transmission wires or cables, these elements being located on said elongated tubular part, preferably at a relatively short distance from the joint, such as a ball joint, which increases its efficiency. Since the wires or cables must remain flexible to facilitate angling control, it is inappropriate to block these wires or cables near the control element, as lengthening of the wires or cables would impair the locking action.
According to one embodiment, the elements gripping the transmission wires or cables in order to lock the aforesaid joint comprise a ring with recesses mounted to rotate about the elongated tubular part and acting by simultaneously jamming all the wires or cables, themselves positioned in lengthwise recesses in the main body of the elongated tubular part. Limited rotation of the ring in a chosen direction locks the transmission wires or releases them.
According to another embodiment, the means gripping the transmission wires or cables in order to lock the aforesaid joint comprise a jamming ring or sleeve mounted to slide in the axial direction of the elongated tubular part and having a frustroconical part acting on the wires or cables. This variant permits xe2x80x9cautomaticxe2x80x9d locking and unlocking control; in particular, unlocking occurs as soon as the control element is activated.
In one particular embodiment, the assembly controlling the angle and rotation of the distal part is translationally movable along the axis of the elongated tubular part and, by means of a cam, controls the jamming and release of the transmission wires or cables, in the case of a rotary jamming ring as described above.
The instrument that is the subject of the invention may also include buttress type locking means located on the handle that act on the axially movable central rod that is connected to the tool control cable in order to maintain the position of this tool, particularly the closure of a forceps.